Tank track and method and apparatus for making same



G. l. MCNEIL May l', 1945.

TANK TRACK AND METHOD AND APPARATUS FO R )MAKING SAME 4 Sheets-Sheet l Filed Jan. 22, 1942 f.. M d.. 0 G

G. 1. MCNEIL May l', 1945.

TANK TRACK AND METHOD AND APPARATUS FOR MAKING SAME Filed Jan. 22, 1942 4 Sheets-Sheet 2 Fig.l /5

G. l. MCNEIL May l, 1945. i

TANK TRACK AND METHOD AND APPARATDS FOR MAKING SAME Filed Jan. 22, 1942 y May 1, 1945.

G. l. McNElI.

TANK TRACK AND METHOD AND APPARATUS FOR MAKING SAME v Filed Jan. 22, -1942 4 Sheets-Sheet 4 fig/6 "6 MG Patented ay VSTE T TRACK AND METHOD APPARATUS FQR .i

Gordon I. McNeil, Akron, Ohio, assigner to Wingfoot Corporation, Akron, Ohio, a corporation of Delaware Application January 2 2, 1942, Serial No. 427,732

16 Claims.

This invention relates to endless tracks for tanks or other fvehicles, and, more specically, to the individualshoes or blocks which when assembled form theendless track, and with improved methods and apparatus formaking the same.

for tanks or other vehicles, the track being formed from a plurality of metal links covered with rubber to Aprovide separate blocks, and with rubber bushings being incorporated in each block. Each of the rubber bushings so incorporated ordinarily comprises an outer metal member of tubular shape, a pin which extends axially of the outer metal member, and 'a body of rubber vulcanized to and between the pin and the outer metal member. The metal links incorporated in each block or shoe are positioned at the sides of the block and are secured to -the ends of the transversely extending outer metal members of the bushings. It has been found that the pounding, bending and wear to which the endless tracks of the character described are subjected in service has caused a concentrationof Wear on eaclr block invthat portion of the block between the tread surface and-the transversely positioned outer metal member of each bushing. It seems that the outer metal member of each bushing acts as anl anvil upon which the rubber positioned between the outer metal member and the surface of the tread is pounded.

Further, the usual process for making-'tractor blocks or shoes of the character described has been to first assemble the pin, rubber, and outer metal member o f each bushing, then connect each pair of bushings with a pair of side links,

and then mold the complete assembly into a large block of rubber.' This process involves a pluralityr o of operations and is relatively expensive.

. wise, under actual service conditions the rubber bushings, asssembled as above described, yield in a radial direction under stress so that the length of the track is or can be increased to the point -where throwing of the track from its supporting and driving means occurs.

It is the general object of my invention to avoid and overcome the foregoing and other v diicultiesof and objections to known tank tracks and tractor blocks, and methods and apparatus block. l

Another object of my invention is to provide a .for making the same, by the provision oi an improved tractor block having a construction which eliminates the concentration of stress between the tread of the block and the outer metal member of each bushing, gives a greater rubber cushioning action and a greater rubber thickness between the tread and the outer metal member of each bushing without increasing the weight or size of the rubber incorporated in the block, and which improves the bond between each rubber bushing and the associated block.

Another object of my invention is to provide an improved method for making tractor shoes or blocks and wherein the rubber incorporated in the bushing or bushings and the rubber forming the Ablock proper is simultaneously flowed into position and vulcanized between the pin and the outer metal member of each bushing and around the outside of the outer metal bushing member and the associated connecting links.

Another object of my invention is the pro- Visionof improved apparatus for facilitating the molding of tractor blocks and the like, and in accordance with which rubber is simultaneously moved into position and vulcanized to form the rubber of the bushing and the rubber of the tractor block or shoe incorporating a pair of rubber bushings therein and with the bushings having greater resistance to radial yield so that the stretching of an endless track formed from the individual blocks is reduced.

Another object of my invention is to provide a tractor block having :longitudinally extending. metal links positioned at the sides of the block and joiningtransversely positioned rubber bushings together with the complete weight of the block being reduced without the sacrifice of strength or function and so that the tendency for an endless track made from'the individual blocks to jump from its supporting or driving means is reduced.

Another object of my invention is the provision is simplified, and in accordance withA which an improved product'results.

Another object of my invention is tn provide animproved block or shoe adapted to form a part of an endless track, said block or shoe including a rubber block having longitudinally ex- -facture of the tractor block.

rotativelyalignthem.

Fig. 9 is a perspective view of a part of the link assembly incorporated in the tractor block of Fig.8;

Fig. 10 is a cross-sectional view ofthe partial linkassemblyshown in Fig. @and taken on line XfX ofFig. 9; 'f

Fig. '1 is a perspective view of metal means used to make the -outer bushing member shown incorporated in the tractor block of Fig. 6;

". Fig.' 12'is a perspective view of the metal member used to make the outer bushing member of the link assembly shown in Figs. 9 and 10, and

facilitating and insuring the,"aecurate 'angular position of the bushing pins during the manu-V The foregoing and other Aolojectsefr'ny'mven. tion are achieved by the provision of a tread shoe n for Aan endless, track, the shoe being of the type including a pair of lon'gitudinallyextending metal links secured together at their ends by .trans' versely extending bushing' members' includingouter metal means and inner metal means joined together by rubber, the links and bushing members `bein'g surrounded by and 'embedded' in a block of rubber,'the tread shoe beingvcharacteriz'ed by' outer metal means'in the bushing members halving'wide clearance spaces through which the rubber ofthe bushing joins the rubber of the block and in the regionv adjacent the tread surface of thebiock. 1 l

The apparatus of my lnvention'comprise's' a incorporated in the tractor block of Fig. 8;

Fig. 13 is a bottom plan view of a tread design which may be incorporated with the tractor block of any 'of the several modiiications:

Fig. 14 is a View similar to Fig. 13 but illustrates another form of tread design;

Fig.' lisl similar-to Figsl'f arid-14 but illustrates' still'anothertread-"design for'tlie tractor -block;""

Fig. 16 is an end elevation, partlyr in section, of a mold adapted to vulcanize any 'one c-f the several tractor blocks illustrated;

Fig. 1'1 is alongitudinal, cross-sectional view taken on line XVII-XVI of Fig. 16; and

Fig. 18 is a plan viewof one of the m'old parts,

v and is taken on line XVIII-XVIII of Fig. 17.

two partmold whi'chis formed with'a recession:-

receivingand supporting the lln'ks and 'outer' bushing members of metal, removable collars re: ceiveciwithin suitable apertures inthe Amold and adapted to support metal pins axially within andf" spaced from the'outerbushing members, and

means carried-by at least one part of the" mold and adapted to' engage with the rmetal pins and iln accordance withthe method'of-fmy inventractor block which: steps' include owi'ng the rub-ff ber between the bushing pins and the bushing members simultaneously'with the owing of the' rubber around'th'e outer bushing members, and vulcanizing the rubber :between thebushing pins-ff around the outer :bushing members.

For a better understanding of; nrvinventionf 'reference vshould be hadxto the"accompanying drawingswherein:

` and outer bushingmembers and simultaneously -1 1 is a fragmentary side elevation' offen r endless track incorporated with a driving and supporting means,=- as for example, :forming a.- partofatankortractorr` Y Flg.-2is a perspectivez'view. partly in section, of'one of the tractor blocks orslioes;incorpor-` A ated iincthe endless track illustrated in Fig. 1:-- I Fl8'.:z3isa perspective view ofi-one of the assemblies forming a( part of the endless track oLFig.- 1, ,with ,therubben block being removedv from thelmk. @sembla Fig. ills .a View parti partly in section'. of. a ,modified formoi tractor. blcm.. y

` ns: s. 1s a' panties, pertain 4agis-pla., of the f in .end Ire"ration and 4tractorblock 'shown in mk. 4

Fig'. 6 is an`endvlew`,"partl5 in section, of another modifled form o'i tractor bloclr.A

y Fig/7 is similar to Flg.- 6 but illustrates sti anothemnodifled form of tractor block: 1

'Flgr-Bt is a viewsimilar to Fixer 6 rand. 'I but:

villustrates yet anothermodied form vo1' tractors` v -75 wide sloten-extend substantialirthe n.111 length bien@ f In the drawingathe numeral 'i0 indicates generally an endlessl track formed fromiaplurality of individual shoes or blocks-22,v 4eachfblock including metal linkage, indicated'as av whole by .the numeral 24, covered with afbodyof rubber 2B. Each yblock '23 also includes a pair of transversely positioned rubber bushings 28 having outer metal members.. 30-which are lsecured totion. I provide a series of steps for 'producing a i member 30, with the ends of the pinf extending laterally beyndthe links 32.

ing-no-ipart ot the .present invention' but comprising, Vas illustrated win Figa-fl,` Cif-shaped tie clamps 86 which engage varound vthe ends of the pins 3i of adjacent blocks, .witha wedge 38 being adaptedto holdthe .ends of .the pins 3% in posi. tion. through .theagency of a clamping bolt 40 securedto the wedge 38 and-'extending through the C-shaped clamp link 36. v'It should be noted that each one of the-Pins. M'of the bushings 2B is providedwith anat spot G2 which isV engaged spect to the .tt-shaped 'link 36. Secured to' the c-,shaped link 36' is 4a `plate M having a radially inwardly extendinglug-i I6 which serves as a guide for the endless track. and which engages with the sides of a fsupp'ortingxwheel' 45 or a driving wheellll ofthe means for-supporting and driving the` endless tracin.v

An important. partici; my advance in the art is to modify -the usual tubular outer metal member ofgeaoh bushing which has caused the objectionable stress concentration Yset forth-.above in the preamble of .the speciflcatloe; One method of accomplishing thestress elimination is illustrated in Figs. 2- and 3 of the drawings whereinthe outer metal member $0 of each-bushing 28 is for-med lwith. a; relatively wide; slot. 58 in-the region adjacent;thetread;surface..58A of eachfblock. The

increase the cushioning thickness of therubberby s of an inch, or even more, on tractor blocks of the relatively small size now being manufactured in production quantities.

Furthermore. the cutting out of the metal to produce the slots 56 effects a saving 'of weight in the complete endless track of as much as 80 to 85 pounds per tank or other vehicle andthis is a direct saving without sacrilce'of .function or strength. Also, the bonding of the rubber of the yblock 2t to the rubber of the bushing and the cutting away of the metal'of the bushing prevents the bushing from acting as an anvil against which the rubber of the block is pounded. A pounding or other stress imparted to the tread surface 58 of the rubber block 2S is absorbed not only by the cushioning action of the rubber between the tread and the bushing but is also absorbed by the rubber of the bushing itself..r Thus, I have found that the life of the type of block illustrated in Fig. 2 is greatly prolonged over the known life of former types of rubber blocks for the reason that the cushioning action is better, a greater thickness of cushioning rubber is provided without any increase in the weight or size of rubber employed, and because a hard anvil surface is not provided by the bushingitself.

Themodifled form of tractor shoe or block illustrated v,in Fig. 4 is generally similar to that already described and illustrated in Figs. l to 3, but the form of the invention shown in Fig. 4 includes aipair of slots 56a and 5th which are cut in the outer metal member 30a of each bushing incorporated in the block. The provision of a pair of slots 56a and 53h in each outer metal member Sila not only facilitates the vulcanization of the block, as hereinafter described, but also provides for improved cushioning action of the block. and, specifically, permits the block to be turned over and operated upside down after theoriginaltread surfaceof the block has become worn. The block assembly shown in Figs. 4 and 5 is in all other respects similar to that alreadyr described and includes side` links 32a connecting the cuter metal members 30a together, and metal pins 3io.

The form of my invention illustrated in Fig. 6

is quite similar to that shown in'Fi'g. 2 except that the edges of the slot or opening 56e provided in each outer metal member 30o by each bushing is formed with rolled-.back or tubular edges 62 whichA tend to reduce and eliminate lany rcutting of the rubber at the end of the slot 56e. This type of outer metal member 30e for each bushing may be made in the manner illustrated inFig. 11 of the drawings `from a long strip of metalwhich is `formed to the desired'cross-sectional contour and is then cut into individual lengths. This manner of forming the outer metal member is more convenient than making the outer metal member in the form `of a tube and thereafter attemptingl to slot the tube and roll, the edges.

The mod iflcatlon of my invention illustrated in Fig '7 is exactly like that shown in Fig. 2V except thatthe rubber block isformedwith a track portion of materially greater thickness than the em- V bodiment of the invention shown inFig. 2. The tread portion of an increased thickness has been indicated by the numeral 64 and obviously this tread may take a plurality of congurations, certain typical configurations being illustrated in Figs. 13 to 15. Fig. 13 shows a chevron design, Fig. 14 shows a parallel bar design, and Fig-15 shows an I-shapedtread contour.

In Fig. 8 I have illustrated still another block or shoe in which the rubber bushing includes an outer metal member 30d formed of a pair of curved metal pieces having rolled or inturned ends 62d. The metal pieces 30d may be formed from a long strip, as shown in Fig. 12, which is bent to the desired cross-sectional contour and cut into appropriate lengths. The separate metal vstrips 30d are brazed or welded to the links 32d in a manner that will be clear from the showing of Figs. 9 and 10.

Turning now to Figs. 16 to 18 I have illustrated one typical form of apparatus for vulcanizing any of the several modifications of the block or shoe of my invention. Specically, the apparatus includes a multi-part mold, indicatedas a whole by the numeral 8b, and generally comprising an upper half 82 and a lower half 861 which are adapted to be joined together in aligned relation which may be assured by the provision of aligning pins 86. Each mold half is formed with' a v ported as a unit. This is achieved byv providing' collars Q6 which extend into the ends of the outer metal members 3@ andwith the collars 9d. being received by -recesses S2 at the'ends of the molds So that all portions of the outer metalmembers 3@ are spaced from the walls of the cavity-e8 and V the links 32 are held in the recesses Sii. The collars @il also support the pins t@ of the bushings in a position axially of the outer metal members 3@ of the bushings. In addition, at least one of the mold halves carries a plate @t which is formed with a pair of openings 9b (see/Fig. i6) .each opening engaging .with the flat spot 32 formed on each pin 3Q. Thus, each pin is properly aligned angularly with the other pins in the mold and is held during vulcanization against rotary movement.

In the use of the apparatus just described, and in accordance with the practice of the method of my invention, I rst provide a flat body of rubber which is positioned in the bottom mold cavity after which the link assembly is mounted in the mold and the collars St are positioned in the lower mold half to receive the pins @d of the block. Thereupon a block of rubber is positioned between the cuter metal members of the llink assembly and a third layer of rubber is positioned on top of the link assembly after which7 the 'upper mold half is moved into position and heat and pressure n bushing, and to simultaneously causea now `of the rubber between the pins 3d and the inner periphery of each outer metal member of the bush- The several metal .parts .of the assembly are appropriately brass-plated, cemented, tie-gum ings.

coated, or Votherwise treated, to facilitate the vulcanization of the rubber thereto and the complete assembly isfvulcanizied. Obviously the slot, slots,-

:cent the tread surface of the block.

I clearances, or openings provided in the outer metal member of each bushing facilitate the iiow of rubber into the bushing proper so that in a single operation the rubber for the bushing and the rubber for the block proper' is vulcanized se-' curely in place.

As an alternative to the method just described, I may provide only a pair of rubber blocks or pieces, each one of which is appropriately formed and grooved, cross-sectionally, as for example, by an extruding operation followed by cutting to length, so that the rubber blocks'will, when positioned in the upper and lower mold halves receive and substantially surround the link assembly. The vulcanizing operation is the same as just described with the mold being placed in a suitable platen press to provide the. necessary molding pressure and with vulcanizing heat being supplied of surrounding steam in amanner` that will be readily understood by a person skilled in the art.

From the foregoing, it will b e recognized that nally extending metal links secured together at their ends by -transversely extending bushing members including outer metal means and inner metal means joined together by rubber, said metal links and bushing members being surrounded byv and embedded in a block of rubber, said shoe being characterized by said outer metal means in the bushing members having wide clearance spaces equal in width to at least about half ofthe diameter of the bushing through which the rubber of the bushing joins the rubber of' the block and in the regions adjacent the tread surface of the block.

3. A tread shoe for an endless track, said shoe being of the type including a pair of longitudinally extending metal links secured together at their ends .by transversely extending bushing to the mold through the platen press o'r by means the various objects of my invention have been achievedby the provision of an improved block or shoe for an endless vehicle Atrack,'and by the provision of improved means and methods for manufacturing the same. provides better cushioning action, has greatly prolonged life, avoids the concentration" of stress between the rubber bushings and the tread surface of the block, is of reduced weight, is less expensive to manufacture,l and functions to resist radial movement of the bushing pins so that the stretch of an endless track madefrom the individual blocks is reduced, often as much as several :inchesA whereby throwing'of the track from the supporting and driving means during use is largely eliminated. My improved apparatus is relatively inexpensive and is readily operated by the ordinary workman to rapidly and uniformly produce my improved tractor block. The method of my invention is rapid, inexpensive, readily performed, and produces under production conditions the high grade improved block or shoe of my invention.

While, in accordance with the patent statutes I have speciiically illustrated and described my invention, it should be understood that I am not the bushing members being shaped to provide a The resulting block? greater rubber thickness'between the tread surout any increase in the distance between the tread surface and the axis' ofthe bushing, and having wide clearance spaces equal in width to at leestabout half of the diameter of the bushing through which the rubber or the bushing joins the rubber of the block and in the regions adja- 2. A tread shoe for an endless track, said shoe being of the type including a pair o longitudi- 'including a'vpair of rubber and metal bushings,

longitudinally extending' laterallyl positioned metal links secured together at their ends by the transversely extending bushings, .each bushing including outer metal means and inner metal means joined together by rubber, said metal links and bushing members being surrounded by and embedded in a block of rubber, the outer metal4 means in' the bushings being formed with wide clearance spaces equal in Width to at least about half of the diameter of the bushing through which the rubber of the bushing joins the rubber oithe y block and in the regions adjacent the tread surface of the block. A 5. A tread shoe for an endless track, said shoe I including a pair of rubber and metal bushings,

longitudinally extending, laterally positioned `metal links secured together at their ends by the transversely "extending bushings, each bushing including outer .metal means and inner metal means joined together by rubber, said metal lmks and bushing members being surrounded by and embedded in a block of rubber, the outer metal means inthe bushings being formed with diametrically opposed wide clearance spaces equal in width'to at least about half of thedameter of the bushing through which-the rubber of the bushing :loins the rubber of the block and in the regions adjacent the tread surface of the block, said block of rubber-being of substantially equalv thickness to the top and bottom side of the bushing axes. 6. A tread vshoe for an endless track, said 'shoe including a pair of rubber and metalbushings laterally positionedI longitudinally extending, metal links securedtogether at their ends by the transversely extending bushings, each bushing including outer metal means and inner'nietal means joined together by rubber, said metal links and bushing members being surrounded by and embedded in a. block ofrubber, the outery metal means in; the bushings being formed withwide clearance spaces through which the rubber of the bushing joins the rubber of the block and in the regions adjacent' the tread surface oftheblock, said outer metal means having rolled-back edges adjacent the clearance spaces.

7. Av tractor block including a body of rubber, a pair of rubber and metal bushings embedded in spaced parallel relation in the body oi rubber, each bushing including a metal tube, a pin extending axially through the metal tube, a sleeve of rubber positioned between the tube and the pin, each tube having a wide slot formed therein toward the tread side of the rubber body and substantially equal in length to thelength of the tube, said rubber sleeve and body beingvulcanized to the pins and tubes, and metal links connecting adjacent ends of the metal tubes.

8. A tractor block including a body of rubber, a pair of rubber and metal bushings embedded in spaced parallel relation in the body of rubber, each bushing including a metal tube, a pin extending axially through the metal tube, a sleeve of rubber positioned between the tube and the pin. each tube having a long wide slot formed therein toward the tread side of the rubber body, said rubber sleeve and body being vulcanized to the pins and tubes, and metal links connecting adjacent ends of 'the metal tubes, said tube adjacent the slot being formed with rolled-back edges toeliminate rubber cutting.

9. A tractor block including a body of rubber, a pair of rubber and metal bushings embedded in spaced parallel relation in the body of rubber, each bushing including a Ametal tube,a pin extending axially through the metal tube, a sleeve of rubber positioned between the tube and the pin, each tube having a pair of opposed long wide slots formed therein toward the upper and lower tread sides of the rubber body, said slots having a. length substantially equal to the length of the tubes and a width equal to at least about one half of the diameter of the tube, said rubber sleeve and body being vulcanized to the pins and tubes Y and to each other, and longitudinally extending,

laterally positioned metal links connecting adjacent ends of the metal tubes. y

10. A in'actor block including a body of rubber. a pair of rubber and metal bushings embedded in spaced parallel relation in the body of rubber, each bushing including a metal tube, a pin extending axially through the metal tube, a sleeve of rubber positioned between the tube .and the pin, each tube having a pair of opposed long wide slots formed therein toward the upper and lower tread sides of the rubber body, said rubber sleeve and body being vulcanized to the pins and tubes and to each other, and longitudinally extending, laterally positioned metal links connecting adjacent end of the metal tubes. said tube adjacent the slots being formed with rolled-back edges toeliminate rubber cutting.

11. A tractor block including a body oi rubber,

a pair of rubber and metal bushings embedded in spaced parallel relation in the body of rubber, each bushing including a metal tube, a pin extending axially' through the meta-l tube, a sleeve of rubber positioned between the tube and the pin, each tube having a plurality of slots formed therein, said slots having a length substantially. equal to the length of the tubes and a width equal to atleast about one half of the diameter of the tube, said rubber sleeve and body being vulcanized to the pins and tubes and to each other through Athe slots, and metal links connecting adjacent ends of the metal tubes.

= l2. A tractor block including a body of rubber. a pair of laterally positioned rubber and metal bushings embedded in spaced parallel relation in the body of rubber, each bushing including a metal tube, a pin extending axially through the metal tube, a sleeve of rubber positioned between the tube and the pin, each tube having a long wide slot formed therein toward the tread side of the rubber body, said slots having a length substantially equal to the length of the tubes and a width equal to at least about one half of the diameter of the tube, said rubber sleeve and body being vulcanized to each other through the sloty and metal links connecting. adjacent ends of the metal tubes.

13. A tractor block including a body of rubber, a pair of rubber andmetal bushings embedded in spaced parallel relation in the body of rubber, each bushing including an outer metal member, a pin extending axially through the metal member,V a sleeve oirubber positioned between the member and the pin, each member having a long wide clearance space therein toward the tread side of the rubber body, said clearance space having a width equal to at least about one half of the diameter of the member and a length substantially equal to the length of the member.

.positioning .a body of rubber against the-bottom vlei. Apparatus for molding tractor blocks, and the like, and comprising a two part mold, said mold being formed with complementary recesses for receiving and supporting within the mold side links and outer bushing members'of metal, removable collars received within suitable apertures in the mold and adapted to support metal pins axially Within and spaced from theouter bushing members, the ends of the metal pins being adapted to extend to the outside of the mold, and means carried by at least one part of, the mold and adapted to engage with the metal pins and rotatively position them.

.15. That method of molding a tractor block for an endless track which includes the steps of positioning a pair of side links joined together with transverse outer bushing members so as to leave the outer surfaces oi. the bushing members exposed, supporting apair of pins axlally of the outer. bushing members, holding the supporting pins in the desired angular relation to each other,

positioning a body of rubber againstl the bottom of the side links and outer bushing members, pb-

sitioning a second body of rubber between the two outer bushing members, positioning a third body of rubber against the top oi the side links and outer bushing members,a.nd applying heat.

and pressure to the three bodies oi' rubber -to cause the rubber to flow around each pin and within each outer bushing member and to ow around the exposed outer surfacey of each outer bushing member and to be vulcanized securely thereto.

16. That method of molding a tractor block for an endless track which lincludes the steps of positioning a pair of side links joined together with transverse outer bushing members so as to leave the outer surfaces of the bushing members exposed, supporting a pair of pins axially of the outer bushing members, holding the supporting pins in the desired angular relation to each other,

of the side links and outer bushing members, po-

sitioning a, second body of rubber against the top v of the side links andouter bushing members. and applying heat and pressure to the two bodies of rubber to Ycause the rubber to flow around each pin and'wlthin each outer bushing member and around the exposed outerA surface oteacho'uter bushing member.

' YGltDON L YMoNEIL. 

